Privacy implications of Monero (XMR) watch-only credentials

When creating a wallet with Trezor in the Monero GUI, you have to export “watch only credentials” which are then stored to disk, encrypted with a password.

I would like to know what are the privacy implications are if those watch-only credentials are stolen/breached. Would the attacker be able to see my transactions and balance on all chains where I have wallets created from the same seed? Or would the attacker only be able to see my Monero balance and transactions?

Generally speaking, the keys that Trezor uses are scoped. Getting ahold of keys for one coin tells you nothing about keys used for different coins. Even if a private key for your Monero was leaked, an attacker can’t use this private key to access any of your other coins.

That implies the answer to your question: if an attacker gets your watch-only credentials, they get to watch your Monero account, but they cannot learn anything about other coins.